Neutral adjustment mechanism for dual lever steering controls

ABSTRACT

A neutral adjustment mechanism for dual lever steering controls. The dual lever steering controls include two levers that are each independently pivotable forward and reverse to drive a zero turning radius mower. The neutral adjustment mechanism includes a control pivot connected to each lever of the dual lever steering controls that pivots with forward and reverse pivoting of each lever. A steering link has a first end with an adjustment point, a ball joint adjacent the adjustment point connecting the steering link to the control pivot, and a second end pivotably connected to an input control lever of a hydrostatic transmission pump. An operator seat may be positioned over the steering links. Under the operator seat, adjustment access holes are provided for adjusting the steering links while the operator seat remains in place.

FIELD OF THE INVENTION

This invention relates to grass mowing machines, and specifically tozero turning radius (“ZTR”) mowers having independently powered left andright drive wheels controlled by a pair of control levers or sticks.

BACKGROUND OF THE INVENTION

Grass mowing machines known as zero turning radius (“ZTR”) mowers haveat least one independently powered drive wheel on each side of a frame.One drive wheel may be operated in a forward direction while the otherdrive wheel may be stopped or operated in reverse. Many ZTR mowers havea twin stick control system. A pair of control levers or sticks may beprovided side-by-side, with each lever or stick controlling one of thedrive wheels. When both levers or sticks are advanced together forwardlyout of their neutral position, both drive wheels rotate forwardly tocause the mower to move forward. A ZTR mower may be steered by advancingone lever or stick more than the other.

Typically, each control lever or stick on a ZTR mower may be linked to apump arm of one of two separate hydraulic pumps, or of a dual hydraulicpump; i.e., a separate pump for each wheel. The lever or stick may beused to move a pump swash plate through a direct linkage.

The control levers or sticks on a ZTR mower may be mounted on thevehicle frame so that each has a first pivot axis allowing the lever orstick in the operating position to pivot forwardly in an arc to turn thewheel in forward, or pivot rearwardly to turn the wheel in reverse.Additionally, the operator can pivot each lever or stick to a neutraloperating position, and then pivot each lever or stick outwardly in anarc to a non-operating or park position. If both levers or sticks arepivoted to neutral, the ZTR mower should be stationary, both levers orsticks should be at the same position, and both levers or sticks shouldalign with slots so that they can pivot outwardly to park. An operatormay need to make neutral adjustments to the linkages if the levers orsticks are misaligned in the neutral position, due to wear, age orloosening of components of the ZTR mower.

Neutral adjustments for levers or sticks on ZTR mowers typically requirethe operator to step off the machine to make the adjustments. Theoperator may have to flip up the seat or remove a panel to access theadjustment points. Once the operator can access the steering linkages,he or she must loosen the links, which may be include turnbuckle and/orjam nuts, to make the adjustments. The operator then must retighten thesteering linkages. The operator also may need to lift the rear of theunit off the ground to prevent the machine from moving during theadjustment.

There is a need for a simple and inexpensive neutral adjustmentmechanism for dual lever steering controls on a ZTR mower that does notrequire the operator to get off the machine while making theadjustments. A neutral adjustment mechanism is needed that does notrequire flipping up a seat, removing a panel, lifting the rear of themachine, or turning off the machine to access the adjustment points. Aneutral adjustment mechanism is needed that allows adjustments to beperformed with minimal effort.

SUMMARY OF THE INVENTION

A neutral adjustment mechanism for dual lever steering controls on a ZTRmower includes a pair of adjustable length steering links, each steeringlink connecting between one of the steering levers and a hydrostatictransmission pump. Each steering link is moveable axially with forwardand reverse pivoting of the steering lever to which it is connected.Each steering link includes an easily accessible adjustment point thatcan be turned to adjust the length of the steering link with minimaleffort and without stepping off the mower, shutting down the mower, ormoving the operator seat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a ZTR mower having a neutral adjustmentmechanism for dual lever steering controls according to a firstembodiment of the invention.

FIG. 2 is a perspective view of a neutral adjustment mechanism for duallever steering controls on a ZTR mower according to a first embodiment.

FIG. 3 is a perspective view of the neutral adjustment mechanism of thefirst embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention may be used with zero turning radius (“ZTR”) mower100 shown in FIG. 1, having at least one drive wheel 101 on each sidethat is independently powered to rotate independently of the other drivewheel. Each independent drive may include a separate hydrostatic drivemotor coupled to each wheel. The pair of drive motors may be connectedvia hydraulic conduits to a dual hydrostatic pump; i.e., a separate pumpfor each wheel. Each side of the dual hydrostatic pump may have a swashplate that may define a pump stroke between a neutral position and afull forward position. The ZTR mower may have a frame 102 supported on aforward end by front wheels 103, and suspending a mower deck 104 betweenthe front and rear wheels. The ZTR mower may have a rear-mounted engine105 behind an operator seat 106. The seat may be mounted over the framefor a seated operator to use left and right control arms 107, here shownin the neutral position. As will be explained in more detail below,linkages between the control arms and dual hydrostatic pump may belocated under the operator seat, and behind panel 108.

Now referring to FIG. 2, left and right motion control levers or sticks107 may be used to drive a ZTR mower. Each control lever or stick may bemounted to the ZTR mower so that the lever may pivot forwardly to move aswash plate in a hydrostatic pump in a first direction to cause a drivewheel to rotate forward, or pivot rearwardly to move the swash plate ina second direction to cause the drive wheel to rotate backward. Eachcontrol lever or stick may have a neutral position in which thecorresponding drive wheel is at rest. The pair of control levers orsticks may be mounted in front of operator's seat 106 on a ZTR mower.

In one embodiment, the lower end of each control lever or stick 107 maybe mounted so that each lever or stick can move independently of theother. In FIG. 1, both levers or sticks are in the neutral position.Each control lever or stick may have a grip 112 at its first or upperend, and may be fastened with bolts through bracket or plate 113 toneutral position lever 114 at its second or lower end. The neutralposition lever may pivot on a first axis defined by shaft or threadedfastener 116 extending through forward/reverse lever 118. Eachforward/reverse lever may pivot on a second axis defined by a transverseshaft or threaded fastener 120 that is perpendicular to the first axis.Control pivot 122 may be connected to each lever of the dual leversteering controls, so that the control pivot can pivot with forward andreverse pivoting of each lever. Control pivot 122 may be integrallyformed with and extend generally rearwardly from forward/reverse lever118. Damper 124 and steering linkage 126 each may be separately fastenedto control pivot 122 as will be explained below.

In one embodiment, steering link 126 may be a rod having a first end 127and a second end 129. The steering link moves axially in response toforward or reverse pivoting of a steering lever to which it isconnected. The steering link may have an adjustment point adjacent thefirst end. Front ball joint 128 may be adjacent the adjustment point,and may connect the steering link to control pivot 122. The second endof the steering link may be pivotably connected to an input controllever of a hydrostatic transmission pump.

In one embodiment, steering link 126 adjacent the first end 127 may beexternally threaded. The adjustment point may be threaded to thesteering link so that it may be rotated to change the position of thesteering link relative to front ball joint 128. The adjustment point canchange the length of the steering link between front ball joint 128 andthe input control lever of a hydrostatic transmission pump. The firstend 127 of the steering link may extend through and beyond front balljoint 128 mounted to control pivot 122. The first end of the steeringlink may be shifted fore or aft by turning adjustment point 133, tochange the length of steering link 126 between front ball joint 128 andhydrostatic pump 136. Washer 134 or resilient collar may be positionedaround steering link 126 between front ball joint 128 and adjustmentpoint 133.

In one embodiment, compression spring 130 may be positioned around thesteering link between front ball joint 128 and stop 132 which may be acollar or threaded fastener on the steering linkage. The second end ofsteering link 126 may be pivotably attached with swivel joint 129 toinput control lever 134 of hydrostatic pump 136. The compression springaround the steering link may provide tightening force against theadjustment point. Damper 124 may be fastened to the frame of the ZTRmower.

In one embodiment, adjustment points 133 are positioned so that they canbe easily accessed from the front end of the ZTR mower. Operator seat106 may be located over the steering links. Panel 108 may be a verticalor near-vertical sheet metal member positioned in front of and below theoperator seat, in front of the steering links. Panel 108 may haveneutral adjustment access holes or openings 137 for adjusting eachsteering link. With the operator seat in place, the seat is above theneutral adjustment access holes, but does not block access to the holes.Each adjustment point 133 is easily accessible behind a neutraladjustment access hole 137 in panel 108 in front of seat 106.Positioning the adjustment points behind neutral adjustment access holes137 allows an operator to make adjustments to steering links 126 fromthe seat or front of a ZTR mower, without removing panels or flippingthe seat. The operator may turn the adjustment points using a controlknob or a socket to adjust each steering link to a neutral position,even while the ZTR mower is running in neutral. Making the adjustmentsto the steering links while operating the mower in neutral may help theoperator obtain correct steering link lengths in the neutral position.

In one embodiment, springs 130 behind front ball joints 128 allowadjustment of steering links 126 to the neutral position withoutloosening linkage hardware. Each spring 130 may be preset to a specifiedspring force, and springs having different rates may be used to obtainsofter or harder feel for the forward/reverse controls. For example, thespring force can be changed to prevent the machine from being tooaggressive in forward or reverse with a rapid control stroke.Additionally, the springs on the steering links can prevent damage tothe ZTR steering system if the operator were to bottom out the stroketransmission while actuating the control levers.

Having described the preferred embodiment, it will become apparent thatvarious modifications can be made without departing from the scope ofthe invention as defined in the accompanying claims.

1. A neutral adjustment mechanism for dual lever steering controlshaving a pair of levers that are each independently pivotable forwardand reverse to drive a zero turning radius mower, comprising: a controlpivot connected to each lever of the dual lever steering controls thatpivots with forward and reverse pivoting of each lever; a steering linkhaving a first end with an adjustment point, a ball joint adjacent theadjustment point connecting the steering link to the control pivot, anda second end pivotably connected to an input control lever of ahydrostatic transmission pump; an operator seat positioned over thesteering link; the adjustment point accessible for changing the positionof the steering link relative to the ball joint to move the levers to aneutral position between forward and reverse while the hydrostatictransmission pump is in a neutral position with the operator seat inplace.
 2. The neutral adjustment mechanism of claim 1 further comprisinga spring between the ball joint and a stop.
 3. The neutral adjustmentmechanism of claim 1 further comprising a damper pivotably connected tothe control pivot.
 4. The neutral adjustment mechanism of claim 1further comprising a panel in front of the steering links and havingneutral adjustment access holes through which the adjustment points canbe accessed.
 5. A neutral adjustment mechanism for dual lever steeringcontrols having two levers that are each independently pivotable forwardand reverse to drive a zero turning radius mower, comprising: a steeringlink connected to each lever, each steering link having a length betweena ball joint and a hydrostatic transmission input control arm, eachsteering link moving axially in response to forward or reverse pivotingof the lever; an adjustment point threaded to each steering link androtatable to change the length of the steering link to bring each leverinto a neutral position between forward and reverse while eachhydrostatic transmission input control arm is in a neutral position; aspring around each steering link to provide tightening force against theadjustment point; and a panel in front of the adjustment points havingneutral adjustment access openings through which each adjustment pointmay be rotated.
 6. The neutral adjustment mechanism of claim 5 furthercomprising a damper connected to each input control arm.
 7. The neutraladjustment mechanism of claim 5 wherein the first end of the steeringlink is threaded.
 8. The neutral adjustment mechanism of claim 5 whereinthe lever is outwardly pivotable in a neutral position.
 9. The neutraladjustment mechanism of claim 5 further comprising an operator seat overthe steering link and neutral adjustment access openings.
 10. A neutraladjustment mechanism for dual lever steering controls having two leversthat are each independently pivotable forward and reverse to drive azero turning radius mower, comprising: a pair of adjustable lengthsteering links, each steering link connecting between one of the leversand a hydrostatic transmission pump, each steering link moveable axiallywith forward and reverse pivoting of the steering lever to which it isconnected; an operator seat over the steering links; and a pair ofaccess holes under the operator seat through which the length of thesteering links may be adjusted without lifting the seat to bring eachsteering lever to a neutral position between forward and reverse whilethe hydrostatic transmission pump is in a neutral position.
 11. Theneutral adjustment mechanism of claim 10 wherein each adjustable lengthsteering link has a threaded end with an adjustment point threadedthereto.
 12. The neutral adjustment mechanism of claim 11 furthercomprising a spring to hold the adjustment point in place.
 13. Theneutral adjustment mechanism of claim 10 further comprising a ball jointbetween each steering link and lever.
 14. The neutral adjustmentmechanism of claim 10 further comprising a damper connected to eachlever.
 15. The neutral adjustment mechanism of claim 10 wherein eachlever is pivotable outwardly from a neutral position.